A common challenge in the technical field of hearing devices is to improve the ability of the hearing-device user to focus attention on a specific speaker in a sound environment with two or more speakers, i.e. to ameliorate the so-called “cocktail-party” effect.
WO2008097201A1 [Guan et al.; 2008] deals with a system and method for processing brain signals in a Brain Computer Interface (BCI) system. The method of processing brain signals in a BCI system comprises the steps of processing the brain signals for control state detection to determine if a subject intends to use the BCI system; and processing the brain signals for command recognition if the control state detection method determines that the subject intends to use the BCI system.
EP2200342A1 [Husung et al.; 2010] deals with a hearing aid comprising a hearing aid component, a brainwave signal receiver configured to receive brainwave signals, and a hearing aid controller configured to control the hearing aid component dependent on the detected brainwave signals.
JP2010082375A [Higuchi; 2010] describes a sound signal processor comprising a brain waveform measuring part, a correlation calculating part for determining a correlation value of each waveform of a plurality of sound signals and a measured brain waveform. An attentively hearing sound specifying part specifies the sound signal having the largest correlation value among the plurality of sound signals as an attentively hearing sound. A weighting and synthesizing part performs weighting so that the sound signal specified as the attentively hearing sound is emphasized more than the other sound signals, and then the plurality of sound signals are synthesized. A sound output part outputs the sound signal synthesized by the weighting and synthesizing part to a headphone or a speaker.
International patent application WO 2011/006681 A1 [Kidmose et al.; 2011] discloses a hearing aid comprising means for modifying the operation of the hearing aid in response to electric signals, such as brainwaves, detected by means of electrodes arranged on and/or in a surface of a part of the hearing aid. The hearing aid may comprise feature extraction means for extracting features from the electric signals and classification means for classifying the extracted features. Examples are given on how brainwave signals may differ when the hearing-aid user focuses his attention either to the music or to the speech in a mixed signal comprising both. It is suggested that when it can be determined to which part of an acoustic image the user pays attention, this information may be used to enable adaptation of the hearing aid to obtain optimum intelligibility of the particular part of the acoustic image. However, details regarding how to distinguish between multiple speakers or how to use such information to adapt the hearing aid are not disclosed.
In an article in Nature, volume 485, p. 233-236, 2012 (‘Selective cortical representation of attended speaker in multi-talker speech perception’) N. Mesgarani and E. F. Chang disclose experimental results that indicate that speech spectrograms reconstructed based on high-gamma cortical responses to acoustic signals comprising a mixture of speakers reveal the salient spectral and temporal features of the attended speaker—as if the subject were listening to that speaker alone. The cortical responses were measured using implanted high-density electrode arrays. The article does not disclose any details as to how this new knowledge could be used, e.g. in hearing devices.